Where is Andrew Heiberger now?

Citi Habitats' offices on Madison Avenue were once a bank, a circumstance that fuels Andrew Heiberger's fantasies. "I keep hoping I'll look in the outside drop and find a pile of money," he says.

That would be nice, but Mr. Heiberger knows how to create his own gold. In 1994, he and partner Igal Feibush founded a rental apartment brokerage that has since become one of the biggest residential companies in the city.

By concentrating on young professionals with modest incomes, the partners tapped into a vibrant group that many other brokerages ignored. To make their fledgling firm seem like landed gentry, they invested in posh offices, top-of-the-line computers and a fat ad budget.

"We were after volume," says Mr. Heiberger, who grew up working for his father, a developer, and brother, a real estate investor.

Today, Citi Habitats has five offices and 175 agents. Last year, it brokered leases worth about $200 million. Mr. Heiberger's first clients came from the wide circle of friends he made growing up in Dix Hills, L.I. He knew that if the brokerage could find them respectable apartments at reasonable rents, they would remain loyal as their incomes grew.

Sure enough, Citi Habitats is now expanding into sales and widening its customer base. "I know how my clients think because they're just like me," says Mr. Heiberger, who proudly calls himself a workaholic. "We're all driven."